While the latest bold attempt by Ubuntu is to put it on TVs and phones in the next two years, this new social effort isn't to build a full-blown social network to compete with (or replace) the likes of Google+ and Facebook. What this new community/social effort is about is just making it easy to find Ubuntu users and Ubuntu events within your geographic area. The idea has been brewing for over one year, but due to devoting resources towards designing the Unity desktop, this idea was largely postponed until now.
Plans for "making community very obvious on the desktop" are still very early, but there's talk of integrating this social functionality directly into the Ubuntu Unity desktop (likely via a Unity lens) that would allow you to find individuals in your town/area that are happy with Ubuntu and about any Ubuntu-related events taking place. "There is a community out there other than a developer community, and it would be nice if we made discovery of this easier. This idea covers ways of providing those hints in the software."
Among the suggestions brought out during the hour-long brainstorming session on the topic was making it more clear when installing Ubuntu that there are millions of users, writing the lens around the Ubuntu LoCo directory, the focus is about helping out new Ubuntu users, and to keep data collection minimal to avoid privacy concerns. The Ubuntu approach would be to build the data slowly with the community.
Action items from this session were to integrate support in the Ubiquity installer for making known the number of Ubuntu users, design mock-ups for Lenses / MeMenu, possible integration with Ask Ubuntu, possible integration with Launchpad, and to expose locations and dates for Ubuntu-related events via other media delivery.
Additional details can be found in this Etherpad notes page. There's also the Launchpad Blueprint. "Most people have no idea whether others in their town/city are using Ubuntu. We need to make community obvious and make community formation easy."